Mystic River is a gripping crime drama that features Laura Linney in a supporting role as Annabeth Markum, the wife of Sean Penn's character. The film revolves around the lives of three childhood friends who are reunited after a tragic event. Linney's character provides a sense of stability and strength amidst the turmoil, showcasing her versatility as an actress. Mystic River is a dark and intense film that delves into themes of friendship, loyalty, and the consequences of past actions.